a writing brush的用法和样例：
- What material is used to make a writing brush?
- There are various kinds of materials that can be used to make a writing brush.
- A writing brush is made of bamboo and animal's hair. This wool jacket is used for keeping warm. Are these stamps made in Australia? Yes, they are.
- Look, Han Jia, what a huge Qi writing brush!
- This is a magic writing brush from Heaven.